Method of transferring a substrate

ABSTRACT

A method of controlling contamination in a substrate transfer chamber that is disposed between a load port for supporting a container to receive a plurality of substrates and a substrate process module for processing the substrates includes supplying a purge gas into the substrate transfer chamber to purge an interior of the substrate transfer chamber, circulating the purge gas supplied into the substrate transfer chamber through a gas circular pipe, removing particles and airborne molecular contaminants from the purge gas being circulated, and resupplying the circulated purge gas into the substrate transfer chamber.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation application based on pending application Ser. No.10/763,203, filed Jan. 26, 2004, the entire contents of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a module for transferring asubstrate. More particularly, the present invention is related to amodule for transferring a substrate between a container to receive aplurality of substrates and a module for processing the substrate.

2. Description of the Related Art

Generally, semiconductor devices are manufactured through a three-stepprocess. First, a fabrication process is performed for formingelectronic circuits on a silicon wafer used as a semiconductorsubstrate. Second, an electrical die sorting (EDS) process is performedfor inspecting electrical characteristics of the semiconductor deviceson the semiconductor substrate. Third, a packaging process is performedfor packaging the semiconductor devices in epoxy resins andindividuating the semiconductor devices.

The fabrication process may include a deposition process for depositinga layer on the substrate, a chemical mechanical polishing (CMP) processfor planarizing a surface of the layer, a photolithography process forforming a photoresist pattern on the layer, an etching process for anelectrical pattern using the photoresist pattern, an ion implantationprocess for implanting predetermined ions into predetermined portions ofthe substrate, a cleaning process for removing impurities from thesubstrate, an inspection process for inspecting the surface of thesubstrate on which the layer or the pattern is formed, or other similarprocesses.

These processes are performed under a high vacuum condition in order toprevent contamination of the semiconductor substrate. To provide thehigh vacuum condition, a substrate process apparatus includes a loadlock chamber maintained under a low vacuum condition, a process chamberin which the process is performed, and a substrate transfer chamber fortransferring the semiconductor substrate between the load lock chamberand the process chamber.

Recently, a substrate process apparatus for some processes (for example,a deposition process or a dry etching process) on a 300 mm semiconductorsubstrate includes a substrate process module, a substrate transfermodule and a load lock chamber. The substrate transfer module includes aload port for supporting a front opening unified pod (FOUP), a substratetransfer chamber disposed between the load port and the load lockchamber, and a substrate transfer robot for transferring thesemiconductor substrate between the FOUP and the load lock chamber.

A fan filter unit (FFU) is connected to an upper portion of thesubstrate transfer chamber. The fan filter unit supplies an interior ofthe substrate transfer chamber with clean air for preventingcontamination of the semiconductor substrate being transferred by thesubstrate transfer robot.

A plurality of exhaust holes is formed through a bottom panel of thesubstrate transfer chamber in order to exhaust the clean air suppliedfrom the fan filter unit out of the substrate transfer chamber or to aclean room in which the substrate process apparatus is provided.

When an internal pressure of the substrate transfer chamber is lowerthan a pressure of the clean room, the air in the clean room may flowback into the substrate transfer chamber, so that the semiconductorsubstrates received in the FOUP and the semiconductor substrate beingtransferred by the substrate transfer robot may be contaminated.Therefore, it is preferable to maintain the internal pressure of thesubstrate transfer chamber higher than the pressure of the clean room.The pressure of the clean room, in which the substrate process apparatusis provided, is generally a positive pressure (i.e., higher thanatmospheric pressure).

For example, a multichamber processing system including acontainer-housing chamber, a cleaning chamber and a load lock chamber isdisclosed in the prior art. The cleaning chamber has an inlet line forintroducing a clean gas into the cleaning chamber and a pressure controldevice for controlling the pressure in the cleaning chamber. Thepressure control device includes a valve for adjusting a flow rate ofthe gas in the inlet line, a differential pressure gauge for detecting adifferential pressure between the pressure in the cleaning chamber andthe atmospheric pressure, and a valve controller for adjusting anopening degree of the valve so that the pressure in the cleaning chamberis maintained at the positive pressure based on a result of thedetecting by the differential pressure gauge.

In addition, wafer atmospheric transport module having a controlledmini-environment is disclosed in the prior art. According to thisexample, a blower located in the top region of an enclosed housing isconfigured to generate a flow of air downward. The airflow generated bythe blower is restricted from freely flowing through a perforated sheetand is partially induced to be redirected toward the shelf, and acassette having one or more wafers is configured to sit on a shelf inthe enclosed housing and thus be subjected to the redirected air flow.

The fan filter unit includes a fan for supplying external air into thesubstrate transfer chamber and a filter for removing particles containedin the external air being supplied into the substrate transfer chamber.However, the filter cannot remove airborne molecular contaminants, suchas organic contaminants, contained in the external air being suppliedinto the substrate transfer chamber. Such airborne molecularcontaminants may cause various defects on the semiconductor substrate.

Examples of the defects may include a variation of a critical dimension(CD) of a photochemical amplified resist pattern and T-top defect causedby ammonia, a natural oxide layer generated by ozone, condensationalcontaminants or the like. Variation of the critical dimension of thephotochemical amplified resist pattern and T-top defect may be detectedin the fabrication process, and operation failure of electrical circuitelements such as transistors due to organic contaminants such as dioctylphthalate (DOP) may be detected in the electrical die sorting process.

SUMMARY OF THE INVENTION

To solve these and other problems, the present invention provides amodule for transferring a substrate that prevents the substrate frombeing contaminated by impurities including particles and airbornemolecular contaminants during transfer of the substrate between a FOUPand a substrate process module.

According to a feature of an embodiment of the present invention, thereis provides a module for transferring a substrate including a load portfor supporting a container to receive a plurality of substrates, asubstrate transfer chamber disposed between the load port and asubstrate process module for processing the substrates, a substratetransfer robot disposed in the substrate transfer chamber fortransferring the substrates between the container and the substrateprocess module, a gas supply unit connected to the substrate transferchamber for supplying a purge gas into the substrate transfer chamber soas to purge an interior of the substrate transfer chamber, and acontamination control unit connected to the substrate transfer chamberfor circulating the purge gas supplied into the substrate transferchamber, resupplying the circulated purge gas into the substratetransfer chamber and removing particles and airborne molecularcontaminants from the purge gas being circulated.

In the module, the container preferably includes a front opening unifiedpod (FOUP). The module may further include a door opener for opening andclosing a door of the FOUP. Also in the module, the gas supply unit mayinclude a gas source for providing the purge gas, a gas supply pipe forconnecting the gas source and the substrate transfer chamber, and a flowcontroller installed in the gas supply pipe for adjusting a flow rate ofthe purge gas being supplied into the substrate transfer chamber.

The purge gas may include a nitrogen gas, and the gas source may includea storage container for storing the nitrogen gas and a purifier forpurifying the nitrogen gas. Alternatively, the purge gas may includeair, and the gas source may include a storage container for storingcompressed air and a purifier for removing impurities contained in theair being supplied from the storage container. The purifier preferablyincludes a molecular sieve purifier or a catalytic purifier.

The contamination control unit may include a gas circular pipeconnecting an upper portion and a lower portion of the substratetransfer chamber, an air pump installed in the gas circular pipe forsucking the purge gas supplied into the substrate transfer chamber andcirculating the sucked purge gas through the gas circular pipe, afiltering part installed in the gas circular pipe for removing theparticles and the airborne molecular contaminants contained in the purgegas being circulated, and a flow controller installed in the gascircular pipe for controlling a flow rate of the purge gas beingcirculated.

The contamination control unit may further include a gas exhaust pipeconnected to the gas circular pipe for exhausting the purge gas beingcirculated and a valve installed in the gas exhaust pipe for opening andclosing the gas exhaust pipe.

The contamination control unit may further include a valve installed inthe gas circular pipe between the lower portion of the substratetransfer chamber and the air pump for opening and closing the gascircular pipe.

The filtering part may include a particle filter for removing theparticles contained in the purge gas being circulated, a moisturepurifier for removing moisture contained in the purge gas beingcirculated, and an organic contaminant filter for removing organiccontaminants contained in the purge gas being circulated. The moisturepurifier is preferably a molecular sieve moisture purifier; the organiccontaminant filter is preferably an activated carbon filter.

The module may further include a distribution panel horizontallydisposed in the substrate transfer chamber, the distribution panelhaving a plurality of holes for uniformly supplying the purge gas intothe substrate transfer chamber, and a particle filter disposed betweenthe distribution panel and the substrate transfer robot for removingparticles contained in the purge gas being supplied through the holes ofthe distribution panel.

Also, an ionizer may be disposed between the distribution panel and theparticle filter for removing static electricity from the substrates.

The purge gas may be an inert gas, and the inert gas may be a nitrogengas. Alternatively, the purge gas may be purified air.

A photo catalyst filter may be disposed between the distribution paneland the particle filter for removing organic contaminants contained inthe purge gas being supplied into the substrate transfer chamber, and anultraviolet lamp for applying ultraviolet rays onto the photo catalystfilter. An ozone filter may be disposed between the photo catalystfilter and the particle filter for removing ozone contained in the purgegas being supplied into the substrate transfer chamber.

A differential pressure sensor may be connected to the substratetransfer chamber for measuring a differential pressure between aninternal pressure and an external pressure of the substrate transferchamber and a control unit for comparing the differential pressuremeasured by the differential pressure sensor with a predetermineddifferential pressure, and for adjusting a flow rate of the purge gasbeing supplied into the substrate transfer chamber and a flow rate ofthe purge gas being circulated through the contamination control unit inaccordance with a comparison result.

A perforated panel may be disposed above a bottom panel of the substratetransfer chamber for passing the purge gas supplied into the substratetransfer chamber therethrough, wherein the perforated panel has aplurality of holes, and the contamination control unit is connected tothe bottom panel of the substrate transfer chamber.

The interior of the substrate transfer chamber is purged by the purgegas supplied from the gas supply unit and the resupplied purge gas fromthe contamination control unit, and thus impurities including particlesand airborne molecular contaminants do not flow into the substratetransfer chamber. As a result, contamination of the substrate due to theimpurities may be prevented.

In addition, the purge gas supplied into the substrate transfer chamberis circulated by means of the contamination control unit, and thus anamount of the purge gas used in the substrate transfer module may bereduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent to those of ordinary skill in the art bydescribing in detail preferred embodiments thereof with reference to theattached drawings in which:

FIG. 1 illustrates a cross-sectional view of a module for transferring asubstrate according to one embodiment of the present invention.

FIG. 2 illustrates a plan view of a substrate process apparatus havingthe substrate transfer module as shown in FIG. 1.

FIG. 3 is a block diagram illustrating operation of the substratetransfer module as shown in FIG. 1.

FIG. 4 illustrates a cross-sectional view of a module for transferring asubstrate according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Korean Patent Application No. 2003-8847, filed on Feb. 12, 2003, andentitled: “Module For Transferring A Substrate,” is incorporated byreference herein in its entirety.

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. The invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

FIG. 1 illustrates a cross-sectional view of a module for transferring asubstrate according to one embodiment of the present invention, and FIG.2 illustrates a plan view of a substrate process apparatus having thesubstrate transfer module as shown in FIG. 1.

Referring to FIGS. 1 and 2, a substrate process apparatus 200 performssome processes, for example, a deposition process for forming a layer ona semiconductor substrate 10 or an etching process for etching the layeron the semiconductor substrate 10 to form an electrical pattern on thesemiconductor substrate 10. The substrate process apparatus 200preferably includes a substrate process module 210 for processing thesemiconductor substrate 10, and a substrate transfer module 300 fortransferring the semiconductor substrate 10 between a container forreceiving a plurality of semiconductor substrates 10 and the substrateprocess module 210. The container preferably includes a front openingunified pod (FOUP) 20.

A pair of load lock chambers 220 is disposed between the substrateprocess module 210 and the substrate transfer module 300.

The substrate process module 210 preferably includes a plurality ofprocess chambers 230 for processing the semiconductor substrates 10, afirst substrate transfer chamber 240 for connecting between the loadlock chambers 220 and the process chambers 230, and a first substratetransfer robot 250 for transferring the semiconductor substrates 10between the load lock chambers 220 and the process chambers 230.

The substrate transfer module 300 preferably includes a load port 302for supporting the FOUP 20, a second substrate transfer chamber 304disposed between the load port 302 and the load lock chambers 220, asecond substrate transfer robot 306 for transferring the semiconductorsubstrates 10 between the FOUP 20 and the load lock chambers 220, a gassupply unit 320 for supplying a purge gas into the second substratetransfer chamber 304 in order to purge an interior of the secondsubstrate transfer chamber 304, and a contamination control unit 340 forpreventing contamination of the semiconductor substrates 10.

Although not shown in detail, the load port 302 supports the FOUP 20 andbrings a door 22 of the FOUP 20 into tight contact with a door 308 ofthe second substrate transfer chamber 304. A door opener 310 for openingand closing the door 22 of the FOUP 20 is provided in the secondsubstrate transfer chamber 304 and is connected to the door 308 of thesecond substrate transfer chamber 304. The door opener 310simultaneously opens the door 22 of the FOUP 20 and the door 308 of thesecond substrate transfer chamber 304.

The second substrate transfer robot 306 is disposed to transfer thesemiconductor substrates 10 in the second substrate transfer chamber304. A driving part 312 for moving the second substrate transfer robot306 horizontally is installed on an inner sidewall of the secondsubstrate transfer chamber 304, and the second substrate transfer robot306 is connected to the driving part 312. However, the second substratetransfer robot 306 may be installed on a bottom panel 314 of the secondsubstrate transfer chamber 304. That is, although the second substratetransfer robot 306 shown in FIG. 1 is connected to the driving part 312,numerous other configurations are possible.

The gas supply unit 320 is connected to an upper panel 316 of the secondsubstrate transfer chamber 304. The gas supply unit 320 preferablyincludes a gas supply pipe 322 connected to the upper panel 316, a gassource 324 for supplying the purge gas, and a first flow controller 326for adjusting a flow rate of the purge gas supplied from the gas source324.

A mass flow controller (MFC) may be used as the first flow controller326, and an inert gas such as nitrogen gas, argon gas or the like may beused as the purge gas.

The gas supply unit 320 preferably supplies the purge gas into thesecond substrate transfer chamber 304, and the gas source 324 preferablyincludes a storage container 328 for storing the purge gas and a gaspurifier 330 for purifying the purge gas. It is preferable that anoxygen content and a water content of nitrogen gas used as the purge gasare less than about 10 ppb. Examples of the gas purifier 330 may includean area purifier, a bulk purifier or the like.

The contamination control unit 340 connected to the second substratetransfer chamber 304 circulates the purge gas supplied into the secondsubstrate transfer chamber 304, resupplies the circulated purge gas intothe second substrate transfer chamber 304, and removes particles andairborne molecular contaminants contained in the purge gas beingcirculated.

The contamination control unit 340 preferably includes a gas circularpipe 342, an air pump 344, a filtering part 346, and a second flowcontroller 348. The gas circular pipe 342 is extended from the bottompanel 314 of the second substrate transfer chamber 304, and is connectedto the gas supply pipe 322 connected to the upper panel 316 of thesecond substrate transfer chamber 304. The air pump 344 is installed inthe gas circular pipe 342, sucks the purge gas supplied into the secondsubstrate transfer chamber 304 through the gas circular pipe 342, andcirculates the sucked purge gas through the gas circular pipe 342. Thefiltering part 346 is installed in the gas circular pipe 342, andremoves the particles and the airborne molecular contaminants containedin the purge gas being circulated. The second flow controller 348adjusts a flow rate of the purge gas purified by the filtering part 346.

The contamination control unit 340 further includes a gas exhaust pipe350, an exhaust valve 352, and a gate valve 354. The gas exhaust pipe350 is connected to the gas circular pipe 342, and exhausts the nitrogengas circulated by the air pump 344. The exhaust valve 352 is installedin the gas exhaust pipe 350, and opens and closes the gas exhaust pipe350. The gate valve 354 is installed in the circular pipe 342 betweenthe second substrate transfer chamber 304 and the air pump 344. A reliefvalve may be used as the exhaust valve 352.

When the flow rate of the circulated purge gas is reduced by operationof the second flow controller 348, pressure in the circular pipe 342 isgradually increased. At that time, the relief valve used as the exhaustvalve 352 compares the pressure in the circular pipe 342 with apredetermined pressure, and adjusts the flow rate of the purge gasexhausted through the gas exhaust pipe 350 in accordance with acomparison result. A proportional control valve may instead be used asthe exhaust valve 352. In this case, the proportional control valveadjusts the flow rate of the exhausted purge gas in accordance with thepressure in the circular pipe 342. Alternatively, the exhaust valve 342may be controlled by a control unit (not shown) for adjusting aninternal pressure in the second substrate transfer chamber 304.

Although the gas exhaust pipe 350 and the exhaust valve 352 are disposedbetween the air pump 344 and the filtering part 346, in FIG. 1, variousother configurations are possible. For example, the gas exhaust pipe 350and the exhaust valve 352 may be disposed between the filtering part 346and the second flow controller 348.

When the air condition of the interior of the second substrate transferchamber 304 is changed abruptly, the gate valve 354 is closed. Forexample, when a side panel of the second substrate transfer chamber 304is opened for maintaining the substrate transfer module 300, the gatevalve 354 is closed so that the purge gas supplied into the secondsubstrate transfer chamber 304 is exhausted through an open portion ofthe second substrate transfer chamber 304. Accordingly, external aircannot flow into the second substrate transfer chamber 304, therebypreventing contamination of the semiconductor substrates 10 by externalair. Furthermore, external air is prevented from flowing into the airpump 344 and the filtering part 346 through the gas circular pipe 342.

The filtering part 346 for removing impurities contained in the purgegas, which is being circulated through the circular pipe 342, preferablyincludes a first particle filter 356 for removing the particles, amoisture purifier 358 for removing moisture, and an organic contaminantfilter 360 for removing organic contaminants such as a volatile organiccompound (VOC).

A high efficiency particulate air (HEPA) filter or an ultra lowpenetration air (ULPA) filter may be used as the first particle filter356, and an activated carbon filter may be used as the organiccontaminant filter 360. A pair of molecular sieve moisture purifiers 358a and 358 b may be used as the moisture purifier 358.

As shown in FIG. 1, the pair of molecular sieve moisture purifiers 358 aand 358 b is disposed between the first particle filter 356 and theorganic contaminant filter 360, and is connected in parallel to the gascircular pipe 342 through a pair of three-way valves 362. When a firstmolecular sieve moisture purifier 358 a is connected to the gas circularpipe 342, a second molecular sieve moisture purifier 358 b is restored.In contrast, the first molecular sieve moisture purifier 358 a isrestored while the second molecular sieve moisture purifier 358 b isconnected to the gas circular pipe 342.

The interior of the second substrate transfer chamber 304 may be dividedinto an upper area 304 a connected with the gas supply pipe 322, a lowerarea 304 c connected with the gas circular pipe 342, and a substratehandling area 304 b for transferring the semiconductor substrates 10between the upper area 304 a and the lower area 304 c.

The upper area 304 a and the substrate handling area 304 b are dividedby a second particle filter 370, and the substrate handling area 304 band the lower area 304 c are divided by a perforated panel 372. A HEPAfilter or an ULPA filter may be used as the second particle filter 370.

A distribution panel 374 is disposed in the upper area 304 a definedbetween the upper panel 316 of the second substrate transfer chamber 304and the second particle filter 370, and has a plurality of holes 374 a.The distribution panel 374 uniformly provides the purge gas suppliedfrom the gas supply unit 320 and the purge gas circulated through thegas circular pipe 342 into the substrate handling area 304 b.

The purge gas supplied into the second substrate transfer chamber 304 isdried by the gas purifier 330 of the gas supply unit 320 and themoisture purifier 358 of the contamination control unit 340. An ionizer376 is disposed between the distribution panel 374 and the secondparticle filter 370. The ionizer 376 removes static electricity from thesemiconductor substrate 10 due to the dried purge gas.

The second substrate transfer robot 306 is disposed in the substratehandling area 304 b. As shown in FIG. 1, the distribution panel 374forms a flow of the purge gas supplied through the gas supply pipe 322into a laminar flow, and the perforated panel 372 assists function ofthe distribution panel 374. The perforated panel 372 has a plurality ofholes 372 a similar to those of the distribution panel 374. Accordingly,the second substrate transfer robot 306 can stably transfer thesemiconductor substrate 10.

In FIG. 1, arrows represent the laminar flow of the purge gas in thesecond substrate transfer chamber 304, and reference designator 380indicates a differential pressure sensor for measuring a differentialpressure between an internal pressure and an external pressure of thesecond substrate transfer chamber 304.

FIG. 3 is a block diagram illustrating operation of the substratetransfer module as shown in FIG. 1.

Referring to FIGS. 1 and 3, the differential pressure sensor 380 isconnected to a control unit 390. The elements already described inconnection with the substrate transfer module 300 shown in FIG. 1 arealso connected to the control unit 390.

The differential pressure sensor 380 measures the differential pressurebetween the internal pressure and the external pressure of the secondsubstrate transfer chamber 304, and sends the measured differentialpressure to the control unit 390. The control unit 390 compares themeasured differential pressure with a predetermined differentialpressure, and controls operations of the first and second flowcontrollers 326 and 348 in accordance with a comparison result. Forexample, when the door 22 of the FOUP 20 is opened by the door opener310, the control unit 390 increases the flow rate of the purge gas fromthe gas supply unit 320 and decreases the flow rate of the purge gascirculated through the gas circular pipe 342. The purge gas suppliedfrom the gas supply unit 320 purges an interior of the FOUP 20, and airinside the FOUP 20 is exhausted through the gas exhaust pipe 350 and theexhaust valve 352. Accordingly, the differential pressure is evenlymaintained at the predetermined differential pressure.

The control unit 390 may suitably control an operation of the exhaustvalve 352 installed in the gas exhaust pipe 350. That is, the controlunit 390 preferably adjusts the flow rate of purge gas exhausted throughthe gas exhaust pipe 350. For example, the control unit 390 suitablycontrols the operations of the exhaust valve 352 and the second flowcontroller 348, thereby adjusting the purge gas being circulated throughthe circular pipe 342.

In addition, the control unit 390 suitably controls operations of theair pump 344 and the gate valve 354, thereby adjusting the flow rate ofthe circulated purge gas. For example, when the side panel of the secondsubstrate transfer chamber 304 is opened for maintenance of thesubstrate transfer module 300, the control unit 390 closes the gatevalve 354, stops the operation of the air pump 344 and then increasesthe flow rate of purge gas being supplied from the gas supply unit 320.As a result, the purge gas supplied into the second substrate 304 isexhausted through the open portion of the second substrate transferchamber 304, and external air cannot flow into the second substratetransfer chamber 304.

Furthermore, the control unit 390 suitably controls operations of thepair of three-way valves 362 such that each of the pair of three-wayvalves is alternately connected with the gas circular pipe 342.

FIG. 4 illustrates a cross-sectional view of a module for transferring asubstrate according to another embodiment of the present invention.

Referring to FIG. 4, a substrate transfer module 400 preferably includesa load port 402 for supporting a FOUP 20, a substrate transfer chamber404 disposed between the load port 402 and a load lock chamber(referring to FIG. 2), a substrate transfer robot 406 for transferringsemiconductor substrates 10 between the FOUP 20 and the load lockchamber, a door opener 410 for opening and closing a door 22 of the FOUP20, a gas supply unit 420 for supplying purge gas in order to purge aninterior of the substrate transfer chamber 404, and a contaminationcontrol unit 440 for preventing contamination of the semiconductorsubstrates 10.

A driving part 412 for moving the second substrate transfer robot 306horizontally is installed on an inner sidewall of the second substratetransfer chamber 404, and the second substrate transfer robot 406 isconnected to the driving part 412.

The gas supply unit 420 is connected to an upper panel 416 of thesubstrate transfer chamber 404, and preferably includes a gas supplypipe 422 connected to the upper panel 416, a gas source 424 forsupplying the purge, and a first flow controller 426 for adjusting aflow rate of the purge gas.

A MFC may be used as the first flow controller 426, and purified air maybe used as the purge gas.

The gas source 424 preferably includes a storage container 428 forstoring compressed air and a purifier for removing impurities containedin the air being supplied from the storage container. The purifierpreferably includes a first purifier 430 for primarily purifying the airand a second purifier 432 for secondarily purifying the primarilypurified air.

The first purifier 430 removes water H₂O and carbon dioxide CO₂contained in the air being supplied from the storage container 428, andthe second purifier 432 removes water H₂O, carbon monoxide CO, sulfuroxides SOx, nitrogen oxides NOx or the like contained in the primarilypurified air. A molecular sieve purifier and a catalytic purifier may beused as the first and second purifiers 430 and 432, respectively.

The contamination control unit 440 is connected to the substratetransfer chamber 404, circulates the air supplied into the substratetransfer chamber 404, and then resupplies the circulated air into thesubstrate transfer chamber 404. Also, the contamination control unit 440removes particles and airborne molecular contaminants contained in theair being circulated.

The contamination control unit 440 preferably includes a gas circularpipe 442, an air pump 444, a filtering part 446, and a second flowcontroller 448. The gas circular pipe 442 is extended from a bottompanel 414 of the substrate transfer chamber 404, and is connected to thegas supply pipe 422 connected to the upper panel 416 of the substratetransfer chamber 404. The air pump 444 is installed in the gas circularpipe 442, sucks the air supplied into the substrate transfer chamber 404through the gas circular pipe 442, and circulates the sucked air throughthe gas circular pipe 442. The filtering part 446 is installed in thegas circular pipe 442, and removes particles and airborne molecularcontaminants contained the air being circulated. The second flowcontroller 448 adjusts a flow rate of the air purified by the filteringpart 446.

The contamination control unit 440 further includes a gas exhaust pipe450, an exhaust valve 452 and a gate valve 454. The gas exhaust pipe 450is connected to the gas circular pipe 442, and exhausts the aircirculated by the air pump 444. The exhaust valve 452 is installed inthe gas exhaust pipe 450, and the gate valve 454 is installed in thecircular pipe 442 between the second substrate transfer chamber 404 andthe air pump 444.

The filtering part 446 for the impurities contained in the air beingcirculated through the circular pipe 442 preferably includes a firstparticle filter 456 for removing the particles, a moisture purifier 458for removing moisture, and an organic contaminant filter 460 forremoving organic contaminants such as a volatile organic compound (VOC).

A HEPA filter or an ULPA filter may be used as the first particle filter456, and an activated carbon filter may be used as the organiccontaminant filter 460. A pair of molecular sieve moisture 458 a and 458b may be used as the moisture purifier 458.

As shown in FIG. 4, the pair of molecular sieve moisture purifiers 458 aand 458 b is disposed between the first particle filter 456 and theorganic contaminant filter 460, and is connected in parallel to thecircular pipe 442 through a pair of three-way valves 462.

The interior of the substrate transfer chamber 404 may be divided intoan upper area 404 a, a substrate handling area 404 b and a lower area404 c.

A distribution panel 474 having a plurality of holes 474 a is disposedin the upper area 404 a. The distribution panel 474 uniformly providesthe air supplied from the gas supply unit 420 and the air circulatedthrough the gas circular pipe 442 into the substrate handling area 404b.

An ionizer 476 is disposed between the distribution panel 474 and asecond particle filter 470. The ionizer 476 removes static electricityfrom the semiconductor substrate 10 due to the dry air supplied into thesubstrate transfer chamber 404.

A photo catalyst filter 478 for removing organic contaminants and anultraviolet lamp 480 for applying ultraviolet rays onto the photocatalyst filter 478 are disposed between the ionizer 476 and the secondparticle filter 470. An aluminum Al mesh coated with titanium dioxideTiO₂ may be used as the photo catalyst filter 478, and it is preferablethat the ultraviolet rays irradiated from the ultraviolet lamp 480 havea wavelength of 254 nm or longer.

The ionizer 476 and the photo catalyst filter 478 cause ozone togenerate from the air supplied through the gas supply pipe 422. Theozone may be removed by means of an ozone filter 482 disposed betweenthe photo catalyst filter 478 and the second particle filter 470.

The substrate transfer robot 406 is disposed in the substrate handlingarea 404 b. The distribution panel 474 forms a flow of the air suppliedthrough the gas supply pipe 422 into a laminar flow, and a perforatedpanel 472 assists function of the distribution panel 474. The perforatedpanel 472 has a plurality of holes 472 a similar to those of thedistribution panel 474. Accordingly, the substrate transfer robot 406can stably transfer the semiconductor substrate 10.

In FIG. 4, arrows represent the laminar flow of the air in the substratetransfer chamber 404, and the reference designators 408 and 484 indicatea door of the substrate transfer chamber 404 and a differential pressuresensor for measuring a differential pressure between an internalpressure and an external pressure of the second substrate transferchamber 404, respectively.

Although not shown in figure, a control unit controls operations of theelements of the substrate transfer module 400, based on the differentialpressure measured by the differential pressure sensor 484.

Further detailed descriptions of these elements will be omitted becausethese elements are similar to those already described in connection withthe substrate transfer module 300 shown in FIGS. 1 and 2.

According to certain embodiments of the present invention, the purge gassupplied from the gas supply unit purges the interior of the substratetransfer chamber. The contamination control unit circulates and purifiesthe purge gas supplied into the substrate transfer chamber, and thenresupplies the circulated/purified purge gas into the substrate transferchamber.

Accordingly, external air cannot flow into the substrate transferchamber, thereby preventing contamination of the semiconductor substratedue to impurities contained in the external air. Furthermore,circulation of the purge gas reduces an amount of purge gas to besupplied from a source.

Preferred embodiments of the present invention have been disclosedherein and, although specific terms are employed, they are used and areto be interpreted in a generic and descriptive sense only and not forpurpose of limitation. Accordingly, it will be understood by those ofordinary skill in the art that various changes in form and details maybe made without departing from the spirit and scope of the presentinvention as set forth in the following claims.

1-22. (canceled)
 23. A method of controlling contamination in a substrate transfer chamber that is disposed between a load port for supporting a container to receive a plurality of substrates and a substrate process module for processing the substrates, the method comprising: supplying a purge gas into the substrate transfer chamber to purge an interior of the substrate transfer chamber; circulating the purge gas supplied into the substrate transfer chamber through a gas circular pipe; removing particles and airborne molecular contaminants from the purge gas being circulated; and resupplying the circulated purge gas into the substrate transfer chamber.
 24. The method as claimed in claim 23, further comprising adjusting a flow rate of the purge gas being supplied into the substrate transfer chamber.
 25. The method as claimed in claim 23, wherein the purge gas comprises an inert gas.
 26. The method as claimed in claim 25, further comprising purifying the inert gas before supplying the inert gas into the substrate transfer chamber.
 27. The method as claimed in claim 23, wherein the purge gas comprises air.
 28. The method as claimed in claim 27, further comprising removing impurities from the air before supplying the air into the substrate transfer chamber.
 29. The method as claimed in claim 23, wherein the purge gas is forcibly circulated by a pump installed in the as circular pipe.
 30. The method as claimed in claim 23, further comprising controlling a flow rate of the purge gas being circulated through the gas circular pipe.
 31. The method as claimed in claim 23, further comprising exhausting a purge gas being circulated in accordance with a pressure in the gas circular pipe.
 32. The method as claimed in claim 23, wherein the airborne molecular contaminants comprise moisture and organic contaminants.
 33. The method as claimed in claim 23, wherein the container comprises a front opening unified pod (FOUP).
 34. The method as claimed in claim 23, wherein the purge gas is supplied through a distribution panel having a plurality of holes into the substrate transfer chamber.
 35. The method as claimed in claim 34, further comprising removing particles contained in the purge gas being supplied through the holes of the distribution panel.
 36. The method as claimed in claim 34, further comprising ionizing the purge gas being supplied through the holes of the distribution panel to remove static electricity from the substrates.
 37. The method as claimed in claim 34, wherein the purge gas is purifies air.
 38. The method as claimed in claim 37, further comprising: removing organic contaminants contained in the purge gas being supplied into the substrate transfer chamber using a photo catalyst filter; and applying ultraviolet rays onto the photo catalyst filter.
 39. The method as claimed in claim 38, further comprising removing ozone contained in the purge gas being supplied into the substrate transfer chamber.
 40. The method as claimed in claim 23, further comprising: measuring a differential pressure between an internal pressure and an external pressure of the substrate transfer chamber; comparing the measured differential pressure with a predetermined differential pressure; and adjusting a flow rate of the purge gas being supplied into the substrate transfer chamber and a flow rate of the purge gas being circulated through the gas circular pipe in accordance with a comparison result.
 41. The method as claimed in claim 23, further comprising simultaneously opening a door of the container and a door of the substrate transfer chamber. 